Solar Radiation
This is the rate at which solar energy reaches the top of Earth's atmosphere at the mean Earth–Sun distance.
What is the solar constant?
The angle between the Sun's rays and the vertical direction.
What is the zenith angle?
This instrument measures global solar irradiance.
What is a pyranometer?
These collectors use mirrors or lenses to concentrate sunlight.
What are concentrating (focusing) collectors?
Solar radiation that reaches the Earth's surface without being scattered
What is beam (direct) radiation?
The angular height of the Sun measured from the horizon.
What is the altitude angle?
This instrument measures only direct beam solar radiation.
What is a pyrheliometer?
This collector uses a long parabolic reflector with an absorber tube at its focus.
What is a parabolic trough collector?
This type of radiation is produced when sunlight is scattered by molecules, dust, and aerosols in the atmosphere.
What is diffuse radiation?
This angle changes by approximately 15° every hour because of Earth's rotation.
What is the hour angle?
The sensing element inside an Eppley pyranometer that produces an emf proportional to solar radiation.
What is a thermopile?
Unlike focusing collectors, this collector receives both direct and diffuse radiation.
What is a compound parabolic collector (CPC)?
The total solar radiation received at the Earth's surface is obtained by adding these two components.
What are beam radiation and diffuse radiation?
This solar angle varies between +23.45° and −23.45° throughout the year.
What is the declination angle?
This instrument records the duration of bright sunshine during the day.
What is the Campbell–Stokes sunshine recorder?
This is the biggest disadvantage of concentrating collectors under cloudy conditions.
What is that they cannot utilize diffuse radiation?
This dimensionless quantity equals 1 when the Sun is directly overhead at sea level.
What is air mass (m = 1)?
This angle is measured between the incoming solar beam and the normal to a surface
What is the angle of incidence?
This quantity is measured by a pyranometer in units of W/m².
What is solar irradiance?
These devices must continuously track the Sun to maintain maximum concentration.
What are concentrating solar collectors?